The present invention relates to a magnetic brush developing method, in particular, to a magnetic brush developing method in which a developer is transported by a developer-retaining member provided with a magnet member therewithin to develop electrostatic latent images.
A magnetic brush developing method is a basic method for developing an electrostatic latent image and includes various types of methods. In such a general method, a magnet member is fixedly arranged within a developer-retaining member and developer held on the developer-retaining member is conveyed by rotating the developer-retaining member existing on an outer circumference of the magnet member to a developing zone to carry out a developing.
However, in this method, an image quality is liable to be influenced by a mixture ratio of toners. That is to say, as the mixture ratio of toners is increased, a relative contacting probability with carriers is reduced and electrification-build-up properties of toners are lowered and thus electrical charging of toners becomes insufficient. Poorly charged toners bring about problems such as toner scattering. As a quantity of toners is relatively further increased, aggregated toners can not be sufficiently crushed by either the mechanical mixing and stirring or the mixing and stirring on the developer-retaining member. The aggregated toners are developed, resulting in the formation of white spots in copied images. In addition, toner foggs become remarkable due to the above described aggregated toners and poorly charged toners.
In particular, as toners having small particle diameters are used and the mixture ratio of toners is increased, the above described tendency appears more remarkably.